Purchase it only if you want a lemon.

An eighth of an inch on a one inch tree?!!

I'd go for it. Negotiate a reduced price because of the flaw. The stock has been picked over all season. None left are top of the line. You can make a point in your favor.

It will heal over rather quickly and not be a problem in my opinion.
Mike......I like Paperbark Maples.

Wound is described as "still about a 3/8 inch gap with dry grey wood showing." "1/8 inch" is the callus tissue.

I still suggest you ignore such a "bargain." That underlying gray wood is dead, dead, dead.

I'd shy away from one with a split in the trunk like that. You might be better off with the split leaders, you can prune one out and train the replacement. Take a look at the roots if you can. In either case ask for a discount.

The split in the trunk is probably not restricting sap flow noticeably, if it's narrow and perfectly vertical, but it's already let in rot fungi.

Height is less important than overall health, and roots are critical.